(* Copyright (C) 2015-2016 Bloomberg Finance L.P.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * In addition to the permissions granted to you by the LGPL, you may combine
 * or link a "work that uses the Library" with a publicly distributed version
 * of this file to produce a combined library or application, then distribute
 * that combined work under the terms of your choosing, with no requirement
 * to comply with the obligations normally placed on you by section 4 of the
 * LGPL version 3 (or the corresponding section of a later version of the LGPL
 * should you choose to use a later version).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)

type untagged_variant = OnlyOneUnknown | AtMostOneObject | AtMostOneArray

type error =
  | Unsupported_predicates
  | Conflict_bs_bs_this_bs_meth
  | Duplicated_bs_deriving
  | Conflict_attributes
  | Expect_int_literal
  | Expect_string_literal
  | Expect_int_or_string_or_json_literal
  | Unhandled_poly_type
  | Invalid_underscore_type_in_external
  | Invalid_bs_string_type
  | Invalid_bs_int_type
  | Invalid_bs_unwrap_type
  | Conflict_ffi_attribute of string
  | Illegal_attribute
  (* we still rqeuire users to have explicit annotation to avoid
     {[ (((int -> int) -> int) -> int )]}
  *)
  | Not_supported_directive_in_bs_return
  | Expect_opt_in_bs_return_to_opt
  | Misplaced_label_syntax
  | Optional_in_uncurried_bs_attribute
  | Bs_this_simple_pattern
  | Experimental_feature_not_enabled of Experimental_features.feature
  | LetUnwrap_not_supported_in_position of [`Toplevel | `Unsupported_type]

let pp_error fmt err =
  Format.pp_print_string fmt
    (match err with
    | Misplaced_label_syntax -> "Label syntax is not support in this position"
    (*
    let fn x = ((##) x ~hi)  ~lo:1 ~hi:2 
    *)
    | Optional_in_uncurried_bs_attribute ->
      "Uncurried function doesn't support optional arguments yet"
    | Expect_opt_in_bs_return_to_opt ->
      "%@return directive *_to_opt expect return type to be \n\
       syntax wise `_ option` for safety"
    | Not_supported_directive_in_bs_return -> "Not supported return directive"
    | Illegal_attribute -> "Illegal attributes"
    | Unsupported_predicates -> "unsupported predicates"
    | Conflict_bs_bs_this_bs_meth ->
      "%@this and %@bs can not be applied at the same time"
    | Duplicated_bs_deriving -> "duplicate @deriving attribute"
    | Conflict_attributes -> "conflicting attributes "
    | Expect_string_literal -> "expect string literal "
    | Expect_int_literal -> "expect int literal "
    | Expect_int_or_string_or_json_literal ->
      "expect int, string literal or json literal {json|text here|json} "
    | Unhandled_poly_type -> "Unhandled poly type"
    | Invalid_underscore_type_in_external ->
      "_ is not allowed in combination with external optional type"
    | Invalid_bs_string_type -> "Not a valid type for %@string"
    | Invalid_bs_int_type -> "Not a valid type for %@int"
    | Invalid_bs_unwrap_type ->
      "Not a valid type for %@unwrap. Type must be an inline variant (closed), \
       and\n\
       each constructor must have an argument."
    | Conflict_ffi_attribute str -> "Conflicting attributes: " ^ str
    | Bs_this_simple_pattern ->
      "%@this expect its pattern variable to be simple form"
    | Experimental_feature_not_enabled feature ->
      Printf.sprintf
        "Experimental feature not enabled: %s. Enable it by setting \"%s\" to \
         true under \"experimental-features\" in rescript.json."
        (Experimental_features.to_string feature)
        (Experimental_features.to_string feature)
    | LetUnwrap_not_supported_in_position hint -> (
      match hint with
      | `Toplevel -> "`let?` is not allowed for top-level bindings."
      | `Unsupported_type ->
        "`let?` is only supported in let bindings targeting the `result` or \
         `option` type."))

type exn += Error of Location.t * error

let () =
  Location.register_error_of_exn (function
    | Error (loc, err) -> Some (Location.error_of_printer loc pp_error err)
    | _ -> None)

let err loc error = raise (Error (loc, error))

let optional_err loc (lbl : Asttypes.arg_label) =
  match lbl with
  | Optional _ -> raise (Error (loc, Optional_in_uncurried_bs_attribute))
  | _ -> ()

let err_if_label loc (lbl : Asttypes.arg_label) =
  if lbl <> Nolabel then raise (Error (loc, Misplaced_label_syntax))
